DESCRIPTION: Dr. Ward demonstrated a long time ago that C. elegans sperm move by events at the surface rather than flagellar power. The major cytoskeletal protein, called msp, assembles into filament bundles which form the motile pseudopod. The PI here proposes to use genetic and molecular approaches to identify regulators of this process. Proposed are: (1) a two-hybrid assay to identify interacting domains of MSP, using mutants that may compensate for one another; (2) the same assay, to analyze candidate interacting proteins as well as screen for new ones; (3) in vitro assays for binding of interacting proteins to MSP dimers and filaments; (4) analysis of the spe6 mutations that either prevent MSP assembly or bypass hermaphrodite spermiogenesis block (this gene is a candidate for the connector between the spermiogenesis initiation signal and the assembly of MSP); (5) analysis of other spe genes that block hermaphrodite spermiogenesis.